Time’s up for New Orleans officials to agree on a plan for paying city firefighters the $75 million — plus $67 million in interest — that it owes them in a decades-old lawsuit, the judge presiding over the case said Thursday.

City officials have two weeks to draw up a proposal and present it in court, Civil District Court Judge Kern Reese told Andy Kopplin, the city’s chief administrative officer, at a hearing.

After that, Reese warned, he might hold city officials in contempt of court or seize city assets to pay the firefighters.

“You got me, Mr. Kopplin? You understand what that means? The handwriting is on the wall,” Reese said, turning in his seat and tracing letters on the wall behind him.

To stave off sanctions from the court, Mayor Mitch Landrieu’s administration must have a plan ready and approved by the City Council by Aug. 21. The council’s next scheduled meeting is Aug. 20.

The case before Reese, known as the “longevity” lawsuit, dates back to 1979, when firefighters sued to get raises that they argued were required by state law based on their years of service.

While firefighters are now being paid the proper amount, successive city administrations have never paid the roughly $142 million in back pay and interest they firefighters are owed, even though the city has lost every round in court.

The dispute over the raises is separate from a so-called “mandamus” lawsuit, which the firefighters brought against the city after the Landrieu administration cut back on the city’s annual contribution to their retirement fund.

The Landrieu administration has argued that it does not have the money to cover the firefighters’ back pay outright without massive cuts to city services and that other legal cases, including two federal consent decrees, the firefighters’ pension case and about $35 million in other judgments against the city, take priority over it.

Administration officials have said any agreement should settle both of the firefighter cases at once. A task force brokered by the New Orleans Business Council last year proposed some plans along that line, but either the firefighters or the city rejected all of them.

Firefighters say they’ve been waiting decades for the money they’re owed and point to more than 100 firefighters who have died while still owed money by the city as the case has moved through the courts.

The two sides have been in mediation over the longevity case in an attempt to come up with a settlement. That fact led Reese to put off a decision on holding city officials in contempt, though Thursday’s hearing suggests his patience has run out.

Firefighters are proposing that the city turn over to them about $20 million of the $45 million it’s getting as part of a settlement with BP. The administration has argued that money should go toward coastal restoration projects or efforts to make the city more resilient against natural disasters.

That money could furnish at least part of a down payment to the firefighters, with the rest of the money to be paid out over the next five years through other sources, including a new property tax given preliminary approval by voters but never put into effect.

Representatives of the firefighters say they’re shooting for the whole amount of the consent judgment, though the actual amount of the payment would likely be whittled down by negotiations or the court.

Another approach was proposed Wednesday by the Business Council. It would tap the unused millage and pay out $45 million to firefighters over 12 years.

Follow Jeff Adelson on Twitter, @jadelson.